<template>
    <div class="canvas">
        <canvas id="canvas" @click="draw()"></canvas>
    </div>
</template>
<script>
export default {
    name: "SIdentify",
    data() {
        return {
            show_num: [],
        };
    },
    methods: {
        //生成并渲染出验证码图形
        draw() {
            let canvas = document.getElementById("canvas"); //获取到canvas的对象，演员
            let canvas_width = canvas.offsetWidth;
            let canvas_height = canvas.offsetHeight;
            let context = canvas.getContext("2d"); //获取到canvas画图的环境，演员表演的舞台
            canvas.width = canvas_width;
            canvas.height = canvas_height;
            let sCode =
                "a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
            let aCode = sCode.split(",");
            let aLength = aCode.length; //获取到数组的长度
            for (let i = 0; i < 4; i++) {
                //这里的for循环可以控制验证码位数（如果想显示6位数，4改成6即可）
                let j = Math.floor(Math.random() * aLength); //获取到随机的索引值
                // let deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
                let deg = Math.random() - 0.5; //产生一个随机弧度
                let txt = aCode[j]; //得到随机的一个内容
                this.show_num[i] = txt.toLowerCase();
                let x = 10 + i * 25; //文字在canvas上的x坐标
                let y = 25 + Math.random() * 8; //文字在canvas上的y坐标
                context.font = "bold 0.3rem 微软雅黑";
                context.translate(x, y);
                context.rotate(deg);
                context.fillStyle = this.randomColor();
                context.fillText(txt, 0, 0);
                context.rotate(-deg);
                context.translate(-x, -y);
            }
            for (let i = 0; i <= 5; i++) {
                //验证码上显示线条
                context.strokeStyle = this.randomColor();
                context.beginPath();
                context.moveTo(
                    Math.random() * canvas_width,
                    Math.random() * canvas_height
                );
                context.lineTo(
                    Math.random() * canvas_width,
                    Math.random() * canvas_height
                );
                context.stroke();
            }
            for (let i = 0; i <= 30; i++) {
                //验证码上显示小点
                context.strokeStyle = this.randomColor();
                context.beginPath();
                let x = Math.random() * canvas_width;
                let y = Math.random() * canvas_height;
                context.moveTo(x, y);
                context.lineTo(x + 1, y + 1);
                context.stroke();
            }
        },
        //得到随机的颜色值
        randomColor() {
            let r = Math.floor(Math.random() * 256);
            let g = Math.floor(Math.random() * 256);
            let b = Math.floor(Math.random() * 256);
            return "rgb(" + r + "," + g + "," + b + ")";
        },
    },
    watch: {
        identifyCode() {
            this.draw();
        },
    },
    mounted() {
        this.draw();
    },
};
</script>
<style lang="less" scoped>
.canvas {
    float: left;
    width: 100px;
    height: 40px;
    #canvas {
        width: 100px;
        height: 40px;
    }
}
</style>

</style>
